1) it's possible to implement SCOM on a VM in Azure as an IaaS configuration to monitor others Azure VMs
Yes. It just like normal SCOM implementation. For detail, you may refer to Chiyo Odika has blog
http://www.concurrency.com/blog/monitoring-azure-iaas-with-operations-manager-2012-the-basics-scom-opsmgr/
http://www.concurrency.com/blog/monitoring-azure-iaas-with-operations-manager-2012-part-2-scom-opsmgr/
2) Operational Insights service
Operation Insights service can apply missing updates to servers in your infrastructure, help you understand server infrastructure capacity, gather event and IIS logs, protect the servers in your infrastructure from malware, comprehensive view into your organizations
IT security posture, assess the risk and health of your server environments on a regular interval and manage alerts from servers monitored by Operations Manager.
It does not replace SCOM functionality on individual machine service monitoring, HD monitoring and performance monitoring.
Roger